In the past, various devices have been developed to transmit gaseous or liquid media at atmospheric pressure from a tube to the internal nasal passages. Such devices generally consist of masks which clamp over the external nasal area or tubes which cannulate the nasal airway. Today, it is highly desirable to transmit air to the nasal passages under pressures greater than atmospheric pressure with a device that is comfortable to wear and which provides a leak-free seal between the device and the nostrils. For certain disorders, such as obstructive sleep apnea, it is important to have a device to deliver air in a free-flowing manner under positive pressure to the nasal air passage of a sleeping individual, and in order to do so, the device must be both comfortable and maintain a seal despite a variety of movements of the head, when the individual is exerting no action to retain the device in position. It is therefore desirable to have a device that is self-retaining and can be tolerated for prolonged periods while providing an adequate seal with the nostrils of an individual.
Many of the prior art devices establish a seal with the nasal airway by insertion of a tube or the bulbous portion of a tube into the nasal air passage. This cannulation of the nasal airway is unacceptable for long-term use, particularly during sleep, inasmuch as any contact of a foreign substance with the internal surface of the nose causes discomfort and nasal and lachrymal secretions.
It would therefore be desirable to have a device that would contact the nostrils, also used interchangeably hereinafter with "nares", and seal to withstand positive pressure, the device being selfretained and presenting aerodynamically contoured, low-resistance pathway for transmission of gases, thereby minimizing the fluctuations of pressure at the nares.